Metabolic Epidemiology Branch, Division of Cancer Epidemiology and Genetics, NCI, Bethesda, Maryland.
Biostatistics Branch, Division of Cancer Epidemiology and Genetics, NCI, Bethesda, Maryland.
Cancer Epidemiol Biomarkers Prev. 2018 Dec;27(12):1480-1482. doi: 10.1158/1055-9965.EPI-17-0900. Epub 2018 Aug 14.
Lowering endogenous estrogen levels is one mechanism whereby physical activity may lower postmenopausal breast cancer risk. Several prospective studies have suggested that increased 2-hydroxylation of estrogens may also reduce postmenopausal breast cancer risk, but whether or not exercise alters estrogen metabolism through this mechanism is unclear.
We measured total circulating concentrations of parent estrogens (estrone and estradiol) and 13 estrogen metabolites, including glucuronidated, sulfated, and unconjugated forms, by stable isotope dilution LC/MS-MS in 153 postmenopausal women randomized to 12 months of moderate-to-vigorous exercise and 153 controls. We also explored associations with cardiorespiratory fitness measured by treadmill.
Although women randomized to exercise averaged 178 minutes/week of exercise over 12 months, their cardiorespiratory fitness was 13% greater than controls at 12 months ( = 0.0001), and total estradiol was reduced by 10% ( = 0.04); there were no statistically significant effects of exercise on circulating concentrations of estrogen metabolites in the 2-, 4-, or 16-pathways, or on the 2-pathway/parent estrogens ratio. However, we observed a statistically significant association between increased fitness and reduced concentration of 2-pathway metabolites ( < 0.05).
We found no evidence that 12 months of moderate-to-vigorous exercise or increased fitness changed estrogen metabolism in a way that might reduce breast cancer risk.
The protective effect of exercise on postmenopausal breast cancer is unlikely to be mediated by changes in estrogen metabolism.
降低内源性雌激素水平是运动降低绝经后乳腺癌风险的一种机制。几项前瞻性研究表明，雌激素的 2-羟化增加也可能降低绝经后乳腺癌的风险，但运动是否通过这种机制改变雌激素代谢尚不清楚。
我们通过稳定同位素稀释 LC/MS-MS 测量了 153 名绝经后妇女的总循环雌酮和雌二醇（雌酮和雌二醇）和 13 种雌激素代谢物的浓度，包括葡萄糖醛酸化、硫酸化和非共轭形式，这些妇女被随机分配到 12 个月的中等至剧烈运动和 153 名对照中。我们还探索了与跑步机测量的心肺功能适应性的关联。
尽管随机运动的女性在 12 个月内平均每周运动 178 分钟，但她们的心肺功能在 12 个月时比对照组高出 13%（=0.0001），总雌二醇降低了 10%（=0.04）；运动对 2-、4-或 16 途径的循环雌激素代谢物浓度或 2-途径/母雌激素比值均无统计学显著影响。然而，我们观察到，体能的增加与 2-途径代谢物浓度的降低呈统计学显著相关（<0.05）。
我们没有发现 12 个月的中等至剧烈运动或增加的体能改变雌激素代谢，从而降低乳腺癌风险的证据。
运动对绝经后乳腺癌的保护作用不太可能通过雌激素代谢的改变来介导。
